I didn't bother with creating a custom holder for the P&S... I just handheld it. Since my P&S (Powershot A650IS can only go max 15sec, for now still feels ok to hand hold it, maybe eventually will create one holder for it)
15sec, f8, ISO 200
But of course, sometimes will have problems like the following that your finger gets caught in the frame.
10sec f8, ISO100
With the above said, I'm not sure how much technology have improved since the age of my P&S vs the newer gen P&S. But shooting long exposure with my A650IS, noise is quite visible even at ISO100.